<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<style>
    .banner{
        width: 500px;
        height: 200px;
        background-color: mediumpurple;
        overflow: hidden;
    }
    .son{
        width: 300px;
        height: 400px;
        background-color: mediumvioletred;
    }
</style>
<body>
<div class="banner">
    <div class="son">

    </div>
</div>
</body>
</html>